No Internet but needing to video conference. Help

I have a small environment that has 15 individuals that work from individual cubicles/workstations throughout the building I’m in. They need to be able to video conference with each other on a regular basis however, the issue is that they have no internet connectivity. Is there a way to use jitsi on my server to allow them to video conference between each other without the internet? I have my Windows 2016 server assigning a static IP addresses to the the specific MAC address of each PC for my team. Is it possible to configure something that can work to allow them to have video conferencing? (i.e. maybe IP can video conference with etc.??) Any help or suggestions are sure appreciated.